Hatchery management of lake trout exposed to chronic dissolved gas supersaturation
Fisheries Bioengineering Symposium: American Fisheries Society Symposium 10
Colt J;White RJ;
American Fisheries Society
Lake trout Salvelinus namaycush can be successfully reared in hatcheries with incompletely degassed water if they are not exposed to supersaturation during their most susceptible ages. Tolerances of lake trout eggs and sac fry for gas supersaturation are high: eggs withstand excess gas pressures of 80 mm Hg (D P, or mm Hg pressure above that of saturation), and sac fry tolerate a D P of 148 mm Hg for 40 d, provided the gas pressure in the water supply does not fluctuate rapidly. Among lake trout reared from eggs at chronic Delta P levels of 10-80 mm Hg, growth decreased and mortality increased 60-80 d after the swim-up stage. For alevins first exposed to high gas levels after 30 d of feeding, growth was slowed and mortality increased within 60 d. Mortality varied with the age of fish, level of supersaturation, and rate and magnitude of change in gas supersaturation.